The German Weather Service (DWD) said the provisional record in Saarbrucken, if confirmed, would surpass the previous all-time high of 41.2C, set on July 25, 2019.
The DWD said several records had been broken on Friday, including Germany's previous June record of 39.6C, measured on June 30, 2019, in the central town of Bernburg.
Other locations also reported extreme heat, with Bad Kreuznach in the state of Rhineland-Palatinate and Kitzingen in Bavaria each reaching 40.7C, according to the weather service.
"The heatwave is going to peak at the weekend, well over 40 degrees in some parts of Germany," said Karsten Brandt, a meteorologist at weather forecasting site Donnerwetter.de.
In France, dozens of people including both young and old have died during the heatwave. Temperatures above 40C have disrupted rail travel and power generation, sparked alcohol bans, suspended schools and postponed outdoor events.
Paris hit a June record of 40.9C on Wednesday.
Even though temperatures were expected to ease, French authorities braced for more casualties.
"There will be consequences in terms of the number of additional deaths," French Health Minister Stephanie Rist told reporters.
In Italy, the heat was expected to intensify into the weekend, bringing temperatures of 40C.
Across western Europe, temperatures soared with 39.4C recorded in the southern Dutch province of Limburg.
In the UK a provisional June record of 37.1C was recorded at Cavendish in Suffolk.
Doctors said the hot weather was affecting critical equipment such as MRI scanners in hospitals across Britain.
In Belgium, a planned re-enactment this weekend of the 1815 Battle of Waterloo - which resulted in the defeat and exile of French emperor Napoleon Bonaparte - was cancelled as a result of the heatwave.
In Austria, the rail company warned that train tracks could buckle in the coming days.
Even Sweden was not immune from the ball of heat rolling across the continent; a cargo train derailed as high temperatures caused track buckling, stopping traffic between Stockholm and the country's second-largest city Gothenburg.
The heatwave has pushed temperatures up to 18C above their seasonal average, according to the Reuters Climate Monitor, and is being driven by a phenomenon known as an Omega block.
This weather pattern traps a bulging ball of hot air over regions for extended periods, with cooler air on its fringes. Demand for electric fans has shot up, and Asian air conditioning makers reported a European sales boom. Most of the housing stock in Northern Europe is not built to temper heat but rather to keep it in.
The present heatwave will begin shifting by the end of the month, hitting Central Europe and the Balkans, the World Meteorological Organisation said.
Scientists said the heatwave would have been virtually impossible without man-made climate change, which has made this week's night-time temperatures 100 times more likely than they would have been even two decades ago.
with DPA
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